This application is based on and incorporates herein by reference Japanese Patent Applications No. 2001-127182 filed on Apr. 25, 2001 and No. 2001-345743 filed on Nov. 12, 2001.
The present invention is related to vehicular power generation control device and method for controlling power generating conditions of a vehicular power generator installed in passenger vehicles and trucks.
A vehicular power generation control device for controlling power generating conditions of a power generator generally has a function for detecting a power generation start by an ignition switch closure. This type of power generation control device performs a control operation so that the power generator starts generating power when the ignition switch closure is detected.
A power generation start detection circuit without the ignition switch closure detection function is disclosed in JP-U-62-44698. This start detection circuit determines whether or not a rotor starts rotating, namely, an onboard engine is started. This determination is made by detecting a frequency of induced voltage in stator windings.
A voltage regulator having both a function for detecting an ignition switch closure and a function for detecting an engine start utilizing residual magnetism is disclosed in JP-A-6-284596. With this device, power generation control can be continued even when a line for detecting the ignition switch closure is broken.
However, the ignition switch closure detection function is one kind of engine start detection functions. Therefore, when using the ignition switch closure detection function with the engine start detection function utilizing residual magnetism, those functions conflict each other. This may cause extra power consumption and unwanted oscillation because the engine start detection function is activated even though the ignition switch closure is already detected.
The first objective of the present invention is to provide a vehicular power generation control device having an ignition switch closure detection function and an engine rotation detection function utilizing a residual flux, as well as reducing power consumption and noise generation.
The second objective is to provide a vehicular power generation control method utilizing ignition switch closure detection and engine rotation detection that are performed without redundancy in order to reduce unnecessary power consumption and noise generation. That is, when ignition switch closure is detected, the rotation detection will not be performed, and when the ignition switch closure is not detected, the rotation detection is performed.
The third objective is to reduce a malfunction of the vehicular power generation control device due to a leak current.
A vehicular power generation control device of the present invention controls output voltages of a vehicular power generator. The power generation control device has the first switching device, a voltage control device, an engine rotation detection device and an ignition switch closure detection device. The first switching device is connected in series with the field winding of the power generator. The voltage control device controls on/off conditions of the first switching device in order to control the output voltage. The rotation detection device detects the output voltage of the stator windings of the power generator to detect the start of engine and starts the operation of the voltage control device. The ignition switch closure detection device detects an ignition switch closure and starts the operation of the voltage control device.
When the ignition switch closure is detected by the ignition switch closure detection device, the device stops the operation of the rotation detection device. Performing the engine start detection by the rotation detection device although the ignition switch closure has been detected results in extra power consumption. An occurrence of unwanted oscillation caused by switching components in each part of the rotation detection device can be reduced. This reduces unwanted noise. Therefore, it is possible to provide a vehicular power generation control device having both ignition switch closure detection function and engine rotation detection function with low power consumption and low noise.
A frequency of phase voltage generated by the residual magnetism is proportional to the number of rotation of the rotor. Therefore, by measuring this frequency to detect the start of engine, a start detection function with high reliability at low cost can be provided in a small space.
When utilizing special-purpose sensors including a rotation sensor, special consideration for a structure is necessary to ensure the reliability. Vehicular power generators are generally used in high temperature and heavily vibrating conditions. Because the space for the power generators is limited, the one that can withstand such environments becomes high in cost and large in size. On the other hand, when detecting the frequency of the phase voltage generated by the residual magnetism, no additional sensor nor space for it is necessary. Moreover, only modification to a part of the circuit is required to implement the detection. As a result, high reliability can be provided at low cost.